Quick picks
One night at 14°F in a RAV4
From Lost in Wonder's video.
Lost in Wonder, a YouTuber with 30,000 subscribers, spent a night in her RAV4 Hybrid at about -10°C (14°F) in Canada and tested what kept her warm. She doesn't name a sponsor. Her main point is the one this whole guide follows: you won't turn the car into a warm cabin, so you build a warm cocoon inside it, and you always have more than one way to stay warm in case one fails.
Her video is in five parts, and so is this guide: the car, the bed and sleeping bag, clothing, safe heat, and safety. We've added the RAV4 details she doesn't cover, like what the hybrid does when you leave it on and which carbon monoxide alarms work in the cold.
1. Get the car ready
Sleep up high on a well-insulated bed
Her bed: a platform, a reflective mat, foam and a mattress. From Lost in Wonder's video.
The cold comes up from below. She sleeps on a raised platform, so there's a layer of air under her, then an insulating mat, then foam, then a mattress. Each layer slows the cold coming up from the floor.
- Look at R value. Sleeping pads are rated by R value, and a higher number means more insulation. The numbers add up when you stack pads.
- Cheap and simple: a closed-cell foam pad like the Therm-a-Rest Z Lite SOL is R 2.0 and about $50 to $60. It can't pop, so it's a good bottom layer.
- Warmest: an insulated air pad like the Therm-a-Rest NeoAir XTherm NXT is R 7.3 and about $230 to $270 at REI. A foam pad under it gives you about R 9.
- For a flat place to sleep in the first place, see our sleeping platform picks.
Cover the windows, shiny side in
From Lost in Wonder's video.
Glass loses heat fast. She covers every window with reflective covers and puts the shiny side toward the inside of the car, so the heat your body gives off bounces back instead of escaping through the glass. They also give you privacy.
- Made for the RAV4: hers are WeatherTech's. The WeatherTech SunShade Full Vehicle Kit for 2019 and later RAV4's (part TS1248K1) is about $220. Sellers list the Adventure for 2019 to 2024 and the TRD Off-Road for 2020 to 2024, so check your trim before you order.
- Do it yourself: cut covers from a roll of reflective bubble insulation like Reflectix to fit each window. Many people glue black fabric to one side so the outside looks plain.
Crack a window, even when it's freezing
From Lost in Wonder's video.
Every breath puts water into the air. In a sealed car, that water ends up on the windows, freezes into ice you have to scrape off the inside, and soaks into your sleeping bag, and a damp bag is a cold bag. She opens a window about 1 to 1.5 inches under a window deflector, the plastic rain guard over the top of the window, so air gets in but snow doesn't.
- WeatherTech's front and rear side window deflectors for the 2019 to 2024 RAV4, hybrid included, are about $104 to $127 a set.
- Fresh air also matters for safety if anything in the car burns fuel. See the safety section.
2. Your sleeping bag and bed
From Lost in Wonder's video.
Pick a bag by its comfort rating
A sleeping bag beats a pile of blankets because it closes around you with no gaps for cold air. The trap is the big number on the bag. Most bags are tested to a standard called ISO 23537, which gives three temperatures, as Rab explains:
| Rating | What it means | Use it for |
|---|---|---|
| Comfort | A typical woman sleeps comfortably, lying relaxed | Picking your bag |
| Limit | A typical man sleeps through the night curled up | The coldest night you'd push it to |
| Extreme | Survival for up to six hours, with a risk of hypothermia | Never plan around it |
Lost in Wonder's advice is to buy a bag rated 5 to 10 degrees colder than the night you expect, more if you sleep cold. Her bag is a down NEMO Sonic -20, about $680 to $750 at REI. Down is the warmest for its size, but it loses warmth when it gets damp, which is another reason to crack a window.
- Add a liner. A fleece liner adds warmth and feels softer than the cold nylon inside most bags. Hers is an electric one.
- Put tomorrow's clothes in the bag. Getting dressed in the morning is far easier when your clothes are warm.
3. What to wear to bed
- Merino wool base layers. They keep you warm, pull sweat away from your skin, and don't smell after a few days without a shower.
- Dry, thick wool socks. Never sleep in the socks you wore all day. Feet sweat even in the cold, and damp socks make cold feet. She adds down booties on top.
- A beanie and a neck warmer, and gloves if your hands get cold. Her fleece-lined hat covers her neck too.
4. Safe ways to make heat
With no power at all
- Hot water bottles. Before bed, boil water and fill two hard-sided bottles; she uses 1.5-liter Nalgenes. Put one at your feet, because warm feet make it much easier to warm the rest of you. Put the other between your thighs, where large blood vessels run close to the skin, so the warmth travels around your body. Close the lids tight and wrap the bottles in a sock so they don't burn you.
- Hand and toe warmers. The stick-on air-activated packets. She puts hand warmers at the tips of her fingers, because that's what freezes first.
- A warm, high-fat meal before bed. Your body makes heat from food. Skip drinks right before bed so you don't have to get up in the night.
- A pee bottle. Opening the door at 2 a.m. lets out all the warmth you've built up. She keeps a lidded bottle in the car for this.
With a power station
- A heated pad or electric blanket. A heated pad under you uses about 12 to 15 watts on low, and a 12-volt camping blanket about 40 to 60 watts on high. She runs an electric liner on high all night and uses about 10% of her Jackery 2000 power station. We cover power stations and how to charge them in our car camping guide.
- Keep the battery warm. Power stations lose capacity in the cold. The Jackery Explorer 2000 Plus is rated to run down to 14°F and to charge only above 32°F, according to its specs. Keep it inside the car with you, and keep your phone in your sleeping bag.
At a campsite with an electric hookup
- With power at the site, she runs her electric pad and blankets and a small electric heater that warms the whole car. Bring a long outdoor extension cord, because the post is often far from where you can park.
- Keep any heater from blowing straight onto fabric, and use one that shuts off if it tips over.
5. Can I leave the RAV4 running all night?
No. A RAV4 makes cabin heat by burning gasoline, and that makes carbon monoxide, which you can't see or smell. The hybrid doesn't get around this.
- The RAV4 Hybrid owner's manual says to turn the hybrid system off when napping, because you can bump the shifter or the pedal, and exhaust can build up. In READY mode, the engine starts on its own whenever it needs to make heat or charge the battery, even if it's quiet when you lie down.
- Snow is the big danger. Snow can bury the tailpipe and push exhaust up into the car, even when you're parked outside. After a big snowfall in Quebec, people were found unconscious in idling cars partly buried in snow, and two others were found dead of suspected carbon monoxide poisoning, as the McGill University Health Centre warned in a CTV News report. NHTSA's winter advice is to keep the exhaust pipe clear of snow and run the car only now and then, just long enough to stay warm.
- The gas RAV4 burns roughly 0.2 to 0.5 gallons an hour idling for heat, according to a car camping site's estimate. That isn't a Toyota number, but it's enough to use a big part of the tank on a long night.
- The RAV4 Prime can run its heater on battery, but owners report its heat pump gives little heat in EV mode below about 25°F, and Prius Prime owners found the engine starts to make heat below about 14°F, in this owner forum thread. So on a truly cold night, the Prime's engine may run too.
If you ever must run the engine to get warm in an emergency, clear the snow away from the tailpipe first, crack a window, run it in short spells while you're awake, and have a working carbon monoxide alarm.
6. Safety
- No flames inside the car. No candles, no propane heaters and no camp stove. They make carbon monoxide and can start a fire. Our car camping guide covers why even small propane heaters like Mr. Heater's Buddy aren't made for sleeping in a car.
- Never rely on one heat source. If your only plan is a power station and it dies in the cold, you need the hot water bottles, the warm bag and the warm clothes to fall back on.
- Check the weather and road conditions before you leave, and tell someone where you're going.
- Winter tires. She admits she doesn't have them, and nearly got stuck leaving camp. See the best snow tires for the RAV4, or rugged tires in winter if you want the all-terrain look.
- A jump starter, a shovel and traction boards. Cold weakens the 12-volt battery, and a jump starter means you don't need another car. Traction boards are the plastic ramps you wedge under a stuck tire.
- A way to call for help without cell service. A satellite messenger lets you text and send an SOS. The Garmin inReach Messenger Plus is about $300 to $500 plus a monthly plan, and ZOLEO's plans start at $20 a month.
Questions you might still have
How cold is too cold?
It depends on your bag and bed more than the car. With a bag whose comfort rating is below the night's low, a well-insulated bed and covered windows, people sleep fine in the teens Fahrenheit, as Lost in Wonder did. If the forecast is colder than your bag's comfort rating, don't go, or plan to sleep at a campsite with power.
What does a basic setup cost?
If you already have a flat place to sleep, a foam pad ($50 to $60) and the WeatherTech window kit (about $220) come to about $270 to $280, plus two hard water bottles. A DIY window kit cuts that a lot. A good winter sleeping bag is the big cost, from a few hundred dollars to about $680 to $750 for hers.
Will my windows frost up inside?
Some frost is normal. Cracking a window and keeping wet boots and clothes in a bag makes a big difference. Wipe the glass in the morning before you drive.
Is the first night the hardest?
She says yes. Your body takes a day to get used to sleeping colder and in more layers, and after that it settles.
Buddy's take
Spend your money on the bed first: a sleeping bag with a comfort rating below the coldest night you'll see, and a foam pad under an insulated pad. That's what keeps you warm when everything else fails.
Then cover the windows and crack one open. The window kit keeps your heat in, and the cracked window keeps your bag dry.
Use free heat before paid heat. Two hot water bottles do more than most gadgets. A heated pad on a power station is a nice extra, but don't count on it in deep cold.
Never sleep with the RAV4 running, hybrid included, and bring a carbon monoxide alarm that's rated to work below freezing.
More car camping guides
Car camping in a RAV4: the complete setup
A flat bed, cold food, power that won't drain your battery, and a warm, bug-free night.
iOverlander for RAV4 campers: what it is and which plan you need
Find campgrounds, free spots on public land and services with notes from other travelers, and decide whether the free version is enough.
Stealth camping in a RAV4: where to sleep and how to blend in
Make your RAV4 look like any parked car, pick a spot where you're allowed to sleep, and know what to do if you get the knock.
- Lost in Wonder's video How to Sleep in a Freezing Car (Without a Heater), December 2025. Photos are stills from the video, credited above.
- Sleeping bag ratings from Rab. Pad R values and prices from Cascade Designs and REI.
- WeatherTech prices from retailer listings at UroTuning and Salmon Speedworx, checked October 11, 2026. Prices change often, so check before you buy.
- Hybrid behavior from the 2025 RAV4 Hybrid owner's manual. Carbon monoxide and snow from the McGill University Health Centre via CTV and NHTSA's winter driving tips. Alarm temperature rating from Kidde's KN-COB-B-LPM page.
- RAV4 Prime heating from owners in this forum thread. Gas idling estimate from AutoRoamer.
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